Attach your pen nib to the end of the feather with superglue. Hold it in place with clear tape while it dries.
After it is dry, cover the tape with black ribbon. (Use black ribbon so the ink won't stain your feather and also so you can't see the tape.
Add decorations if desired to suit your needs or taste.

*The magical qualities of feathers are determined by their color (and, sometimes, by the birds from which they fell).
Below is a composite of feather lore from (mostly) European folk magick sources, and it differs from that of color symbolism in general.
It's always best to use found feathers as opposed to purchased feathers.
Walks in parks, or in zoos, can provide a wealth of materials.
If you keep birds, you have an even more reliable supply. Never harm a bird to obtain a feather.